// Example 18.19, page no-472
clear
clc
epsr=1.0000684
N=2.7*10^25//m^-3
eps=8.854*10^-12
alfe=eps*(epsr-1)/N
printf("The electronic polarisability of He atoms at NTP is %.3f *10^-41 F.m^2",alfe*10^41)